.fixed-fullscreen {
    position: fixed;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
}
.fixed-fullscreen-mask {
    position: fixed;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0,0,0,.33);
}
.absolute-fullscreen {
    position: absolute;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
}
.absolute-transform-center {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
}
.fixed-transform-center {
    position: fixed;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
}
.absolute-margin-center {
    .absolute-fullscreen;
    margin: auto;
}
.fixed-margin-center {
    .fixed-fullscreen;
    margin: auto;
}
.flex-center {
    display: flex;
    justify-content: center;
    align-items: center;
}
